Artificially produced polyclonal immunoglobulin preparation

ABSTRACT

The present invention intended to provide an artificial polyclonal immunoglobulin composition having a high therapeutic effect and high safety, and being capable of stable supply in a large amount. Specifically provided is an artificial polyclonal immunoglobulin composition containing, as active ingredients, 204 polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing, the polypeptides being plural kinds of single chain variable fragments (also referred to as ScFvs) each comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin, in which the heavy chain variable regions are different each other.

TECHNICAL FIELD

The present invention relates to an artificial polyclonal immunoglobulin composition. More specifically, the present invention relates to an artificial polyclonal immunoglobulin composition containing, as active ingredients, plural kinds of single chain variable fragments (also referred to as ScFvs) each comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin, in which the heavy chain variable regions are different each other. Further, the present invention relates to a therapeutic method for an infectious disease or an inflammatory disease, the method including administering the artificial polyclonal immunoglobulin composition according to the present invention, and to use of the artificial polyclonal immunoglobulin composition according to the present invention, in production of a pharmaceutical composition for treating an infectious disease or an inflammatory disease.

BACKGROUND ART

Immunoglobulin (Ig) is a generic term for antibodies and proteins structurally or functionally related to the antibodies. That is, when an antigen to which an immunoglobulin binds has been revealed, the immunoglobulin is called an antibody in association with the particular antigen. In a basic molecular structure of the immunoglobulin, two each of two kinds (small and large) of polypeptides, i.e., light chains (also referred to as L chains) and heavy chains (also referred to as H chains) are linked together by disulfide bonds. The heavy chain has a structure consisting of a constant region (also referred to as C region) comprised of three domains (CH1, CH2, and CH3) and a variable region (also referred to as V region) comprised of a VH domain, both regions of which is being linked together. In the immunoglobulin except IgM and IgE, there is a peptide called a hinge region between CH1 and CH2. The light chain has a structure consisting of a constant region comprised of a CL domain and a variable region comprised of a VL domain, both regions of which are being linked together. The variable regions are found to have diversity in amino acid sequence, and thus various antibodies against various antigens are produced in a living body.

A hitherto clinically used immunoglobulin preparation is a blood preparation obtained by concentrating immunoglobulins extracted from human blood, and has an action of protecting a living body by causing antigen-antibody reactions with foreign invaders such as bacteria. In recent years, the immunoglobulin preparation has been being used for, for example, idiopathic thrombocytopenic purpura, agammaglobulinemia, the acute phase of Kawasaki disease, Guillain-Barré syndrome, and Churg-Strauss syndrome as vasculitis as well as a severe infectious disease. In addition, in the treatment of those diseases, an “IVIg therapy” involving high dose intravenous administration of immunoglobulins has been frequently employed. Recently, the IVIg therapy has attracted attention as a therapeutic method for refractory vasculitis or the like, and has been internationally regarded as important as a therapeutic method for various diseases as well. In addition, the IVIg therapy has been approved for an autoimmune disease, and in association with this, the IVIg therapies have been started for connective tissue disease and myasthenia as targets in succession. Further, the IVIg therapy has a 20-year history of Kawasaki disease treatment, and has been recently approved as being more effective in single-dose administration at 2 g/kg body weight. As described above, IVIg is extremely effective for a high-severity disease and a refractory disease of unknown cause. Further, IVIg is a useful therapeutic method also because of having virtually no side effects.

There are some hypotheses about an action mechanism of the immunoglobulin preparation. One hypothesis is such that the immunoglobulin preparation contains many kinds of antibodies including antibodies against unknown antigens and thus exert pharmacological effects. Further, another hypothesis is such that antibodies against myeloperoxidase (MPO) (anti-MPO antibodies) among the many kinds of antibodies have the effects, and in particular, many kinds of anti-MPO antibodies against a wide range of epitopes of MPO exert the pharmacological effects. What is common to both the hypotheses is that the therapeutic effect is significantly contributed by the fact that the immunoglobulin preparation is a mixture of multiple immunoglobulins, i.e., polyclonal immunoglobulins. Though there are other hypotheses, the two hypotheses given as examples are each a popular one.

An immunoglobulin preparation clinically used at present is a blood preparation, and hence always involves such a risk that an unknown pathogen such as a virus derived from a raw material may be mixed therein. In fact, a blood preparation contaminated with a pathogenic virus has caused medication-related harm, becoming a serious social issue. In addition, in association with an increase in the number of diseases to be treated, a shortage of blood serving as a raw material is predicted, and hence the immunoglobulin preparation as a blood preparation is unreliable in terms of stable supply.

Under such circumstances, in order to reduce an infection risk for a patient and reveal the process of healing by the immunoglobulin preparation, there is a demand for an artificial, synthesized immunoglobulin preparation. For producing the artificial immunoglobulin preparation, the following method has been carried out. The method involves obtaining a gene of an immunoglobulin, expressing the gene by using a recombinant DNA technology, and obtaining a purified immunoglobulin. For example, a chimeric antibody obtained by replacing only a variable region of an immunoglobulin with a mouse-derived one (Japanese Patent Application Laid-open No. Hei 5-304989), and a humanized antibody obtained by replacing only a CDR region in a variable region with a mouse-derived one (Japanese Patent Application Laid-open No. 2000-14383) can each be produced by a recombinant DNA technology. The chimeric antibody and the humanized antibody have already been put to practical use as antibody drugs. Further, as a technology for expressing an immunoglobulin gene as a normal soluble protein in host cells, there is known an example in which an immunoglobulin is expressed as a fusion protein with a chaperonin (Japanese Patent Application Laid-open No. 2004-81199). However, each of those preparations comprises a single kind of immunoglobulin, i.e., a monoclonal immunoglobulin. Further, the properties of cDNA clones are not stable, and hence the quality of purified products is not stable. Thus, the immunoglobulin preparation has problems in therapeutic effect and quality control.

REFERENCE LIST Non-Patent References

-   [Patent Reference 1] Japanese Patent Application No. Tokkai-Hei     5-304989. -   [Patent Reference 2] Japanese Patent Application No. Tokkai     2000-14383. -   [Patent Reference 3] Japanese Patent Application No. Tokkai     2004-81199. -   [Patent Reference 4] Japanese Patent Application No. Tokkai     2005-312445.

SUMMARY OF INVENTION Problem to be Solved by the Invention

An artificial immunoglobulin preparation that replaces a blood preparation has been demanded to be provided. As described above, however, the currently produced artificial immunoglobulin is a monoclonal immunoglobulin, and hence has problems in therapeutic effect and quality control of the immunoglobulin preparation.

The effect of the artificial immunoglobulin preparation is significantly contributed by the fact that the preparation is a mixture of multiple immunoglobulins, i.e., polyclonal immunoglobulins. The production of the polyclonal immunoglobulin mixture may be carried out by preparing plural kinds of recombinant vectors corresponding to multiple immunoglobulin variable regions to prepare a recombinant vector mixture, and expressing plural kinds of polypeptides corresponding to the multiple immunoglobulin variable regions in a recombinant organism to prepare a mixture of the polypeptides. However, the artificial polyclonal immunoglobulin mixture produced by such method has a problem in that the properties of purified products are not stable.

In order to solve the problem, the inventors of the present invention have devised a production method for an artificial polyclonal immunoglobulin, the method including preparing a mixture of vectors for expressing plural kinds of genes each encoding a single chain variable fragment (ScFv) comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin (Japanese Patent Application Laid-open No. 2005-312445).

A problem to be solved by the present invention is to provide an artificial polyclonal immunoglobulin composition that shows a high therapeutic effect and safety, and is capable of being supplied stably in a large amount.

In order to solve the problem, the inventors of the present invention have produced a mixture of plural kinds of single chain variable fragments (ScFvs) each comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin, in which the heavy chain variable regions are different each other, from cDNAs derived from tissues or cells expressing immunoglobulins by using a recombinant DNA technology, and have tested its effect through the use of vasculitis model mice. As a result, the inventors have found that a mixture of 204 polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing alleviates vasculitis symptoms in vasculitis model mice. Thus, the present invention has been completed.

That is, the present invention relates to the following:

1. an artificial polyclonal immunoglobulin composition, comprising, as active ingredients, polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing;

2. a pharmaceutical composition for treating an infectious disease or an inflammatory disease, comprising polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing;

3. a pharmaceutical composition for treating of vasculitis, comprising polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing;

4. a method of treating an infectious disease or an inflammatory disease, comprising administering an artificial polyclonal immunoglobulin composition comprising, as active ingredients, polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing;

5. the method according to the item 4, wherein the infectious disease or the inflammatory disease is vasculitis;

6. a use of polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing, in production of a pharmaceutical composition for treating an infectious disease or an inflammatory disease; and

7. the use according to the item 6, wherein the infectious disease or the inflammatory disease is vasculitis.

According to the present invention, there can be provided an artificial polyclonal immunoglobulin composition containing, as active ingredients, plural kinds of single chain variable fragments (ScFvs) each comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin, in which the heavy chain variable regions are different each other, the composition being produced from cDNA derived from tissues or cells expressing immunoglobulins by using a recombinant DNA technology. For example, it is possible to provide the artificial polyclonal immunoglobulin composition containing, as active ingredients, the 204 polypeptides represented by the amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing.

The artificial polyclonal immunoglobulin composition according to the present invention contains multiple immunoglobulins as with a blood-derived immunoglobulin preparation. Thus, the artificial polyclonal immunoglobulin composition according to the present invention has a high therapeutic effect, and high safety by virtue of an extremely low infection risk, and is capable of being stably supplied in a large amount. Therefore, the artificial polyclonal immunoglobulin composition according to the present invention is extremely useful for an IVIg therapy.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating the cloning of a human single chain variable fragment (hScFv) (Example 1).

FIG. 2 is a diagram illustrating a schedule according to which the therapeutic effect of a mixture comprised of plural kinds of hScFvs was tested with SCG/Kj mice as spontaneous vasculitis model mice (Example 2).

FIG. 3 is a graph showing that the administration of the hScFv mixture gave a reduction in MPO-ANCA level in serum as an indicator for vasculitis (Example 2). In the figure, symbol “*” indicates the presence of a significant difference (P<0.05).

FIG. 4 is a graph showing that the administration of the hScFv mixture gave a decreasing tendency of a spleen weight (Example 2).

FIG. 5-A is a graph showing that the administration of the hScFv mixture gave a decreased leukocyte count and decreased lymphocyte count in peripheral blood (Example 2). In the figure, symbol “*” indicates the presence of a significant difference (P<0.05).

FIG. 5-B is graphs showing that the administration of the hScFv mixture gave a decreased monocyte count and decreased granulocyte (neutrophil) count in peripheral blood (Example 2).

FIG. 5-C is a graph showing that the administration of the hScFv mixture gave a decreased platelet count in peripheral blood (Example 2). In the figure, symbol “*” indicates the presence of a significant difference (P<0.05).

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to an artificial polyclonal immunoglobulin composition. More specifically, the present invention relates to an artificial polyclonal immunoglobulin composition containing, as active ingredients, plural kinds of single chain variable fragments (ScFvs) each comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of an immunoglobulin, in which the heavy chain variable regions are different each other.

A polyclonal immunoglobulin composition means a composition containing plural kinds of immunoglobulins which antigen specificities are different.

The artificial polyclonal immunoglobulin composition according to the present invention is preferably an artificial polyclonal immunoglobulin composition containing, as active ingredients, 204 polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing. Each of those polypeptides is a human single chain variable fragment (hScFv) comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH1-hinge) of a human gamma globulin, and is a polypeptide produced from RNA extracted from healthy adult peripheral blood mononuclear cells by using a recombinant cDNA technology.

The artificial polyclonal immunoglobulin composition according to the present invention may be produced as a pharmaceutical composition containing a pharmaceutically acceptable carrier (pharmaceutical carrier) as required.

Examples of the pharmaceutical carrier may include a filler, an extender, a binder, a moisture imparting agent, a disintegrating agent, a lubricant, a diluent, and an excipients, which can be generally used depending on the form of use of the pharmaceutical preparation. These can be suitably selected and used depending on the form of administration of the pharmaceutical preparation obtained. More specific examples thereof may include water, a pharmaceutically acceptable organic solvent, collagen, polyvinyl alcohol, polyvinylpyrrolidone, a carboxyvinyl polymer, sodium alginate, water-soluble dextran, sodium carboxymethylstarch, pectin, xanthan gum, gum arabic, casein, gelatin, agar, glycerin, propylene glycol, polyethylene glycol, vaseline, paraffin, stearyl alcohol, stearic acid, human serum albumin, mannitol, sorbitol, and lactose. One or a combination of two or more kinds of these carriers may be used depending on the dosage form of the composition. In addition, there may be appropriately used, for example, a stabilizing agent, a bactericide, a buffer, a tonicity adjusting agent, a chelating agent, a surfactant, and a pH adjusting agent. Examples of the stabilizing agent may include human serum albumin, a general L-amino acid, a saccharide, and a cellulose derivative. The L-amino acid is not particularly limited, and may be any of L-amino acids such as glycine, cysteine, and glutamic acid. The saccharide is also not particularly limited, and may be any of saccharides such as: a monosaccharide, e.g., glucose, mannose, galactose, or fructose; a sugar alcohol, e.g., mannitol, inositol, or xylitol; a disaccharide, e.g., sucrose, maltose, or lactose; a polysaccharide, e.g., dextran, hydroxypropylstarch, chondroitin sulfate, or hyaluronic acid; and a derivative thereof. The cellulose derivative is also not particularly limited, and may be any of cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, and sodium carboxymethyl cellulose. The surfactant is also not particularly limited, and any of an ionic surfactant and a nonionic surfactant may be used. Examples of the surfactant include a polyoxyethylene glycol sorbitan alkyl ester-based surfactant, a polyoxyethylene alkyl ether-based surfactant, a sorbitan monoacyl ester-based surfactant, and a fatty acid glyceride-based surfactant. Examples of the buffer may include: boric acid, phosphoric acid, acetic acid, citric acid, γ-aminocaproic acid, and glutamic acid; and/or a salt thereof (e.g., alkali metal salts thereof and alkali earth metal salts thereof, such as a sodium salt thereof, a potassium salt thereof, a calcium salt thereof, and a magnesium salt thereof). Examples of the tonicity adjusting agent may include sodium chloride, potassium chloride, saccharides, and glycerin. Examples of the chelating agent may include sodium edetate and citric acid.

Total amount of the active ingredients contained in the artificial polyclonal immunoglobulin composition according to the present invention can be suitably selected from a wide range. A suitable amount is generally within a range of approximately 0.00001 to 70 wt %, preferably approximately 0.0001 to 5 wt %.

Dosage range of the artificial polyclonal immunoglobulin composition according to the present invention is not particularly limited, and is suitably selected depending on, for example, effectiveness of the ingredients contained therein, an administration form, an administration route, the type of disease, the properties of a subject (such as a body weight, an age, a condition, and whether a subject is taking other pharmaceutical agents), and a judgment by a doctor in charge. A suitable dosage is, for example, within a range of about from 0.01 μg to 100 mg, preferably about 0.1 μg to about 1 mg, per 1 kg of body weight of the subject. However, such dosage can be altered using conventional experiments for optimization of a dosage that are well known in the art. The aforementioned dosage can be divided for administration once to several times a day. Further, as required, a large amount of the composition may be administered with reference to a dose employed in a hitherto performed IVIg therapy.

In terms of a route of administration, either systemic administration or local administration may be selected. In this case, a suitable administration route is selected depending on a disease, symptoms and the like. The composition according to the present invention may be administered by any of an oral route and a parenteral route. Examples of the parenteral route may include subcutaneous, intradermal, and intramuscular administration as well as general intravenous administration and intraarterial administration. Among them, intravenous administration is more preferred. Particularly when a large amount of the composition is administered in an IVIg therapy, the composition is preferably administered by intravenous administration.

A dosage form is not particularly limited, and various dosage forms may be adopted. For example, the composition may be used as a solution preparation, or may be lyophilized so as to be storable and then dissolved at time of use in, for example, water, a buffer solution containing physiological saline, or the like so as to be prepared at an appropriate concentration before use. Further, the dosage form may be a sustained dosage form or an extended release dosage form.

Specific examples of the parenteral drug may include, but not limited to, injections such as an intravenous injection, a subcutaneous injection, an intramuscular injection, and an intraperitoneal injection, a patch, ointment, and lotion for transdermal administration, sublingual medicine and a patch for application to oral-cavity mucosa for buccal administration, an aerosol for transnasal administration, and a suppository. For oral administration, the following forms may be adopted: a tablet, a capsule, a powder, a granule, a pill, a liquid, an emulsion, a suspension, a solution, a spirit, a syrup, an extract, and an elixir. Those preparations may be produced by a known method generally employed in a formulation process.

In the case of preparing the injection, subcutaneous, intramuscular, and intravenous injections can be produced by a conventional method through the addition of a pH adjusting agent, a buffer, a stabilizing agent, a tonicity adjusting agent, a local anesthetic, and the like to the above-mentioned compound. In such a case, examples of the pH adjusting agent and the buffer may include sodium citrate, sodium acetate, and sodium phosphate. Examples of the stabilizing agent may include sodium pyrosulfite, ethylenediamine tetraacetic acid (EDTA), thioglycolic acid, and thiolactic acid. Examples of the local anesthetic may include procaine hydrochloride and lidocaine hydrochloride. Examples of the tonicity adjusting agent may include sodium chloride and glucose.

In the case of preparing a solid preparation for oral administration, a tablet, a coated tablet, a granule, a powder, a capsule, and the like can be produced by a conventional method after the addition of an excipient and as required, a binder, a disintegrating agent, a lubricant, a colorant, a taste masking agent, an odor masking agent, and the like to the above-mentioned active ingredients. An additive generally used in the field can be used as such additive. Examples of the excipient may include lactose, white soft sugar, sodium chloride, glucose, starch, calcium carbonate, kaolin, microcrystalline cellulose, and silicic acid. Examples of the binder may include water, ethanol, propanol, a simple syrup, a glucose solution, a starch solution, a gelatin solution, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropylstarch, methyl cellulose, ethyl cellulose, shellac, calcium phosphate, and polyvinylpyrrolidone. Examples of the disintegrating agent may include dry starch, sodium alginate, powdered agar, sodium hydrogen carbonate, calcium carbonate, sodium lauryl sulfate, stearic acid monoglyceride, and lactose. Examples of the lubricant include purified talc, a stearate, borax, and polyethylene glycol. Examples of the taste masking agent may include white soft sugar, bitter orange peel, citric acid, and tartaric acid.

In the case of preparing a liquid preparation for oral administration, an internal liquid, a syrup, an elixir, and the like can be produced by a conventional method through the addition of a taste masking agent, a buffer, a stabilizing agent, an odor masking agent, and the like to the above-mentioned compound. In such a case, examples of the taste masking agent may include the above-mentioned agents, examples of the buffer may include sodium citrate, and examples of the stabilizing agent may include tragacanth, gum arabic, and gelatin.

The artificial polyclonal immunoglobulin composition according to the present invention is useful for the treatment of a disease for which a therapy by immunoglobulin administration, e.g., IVIg is effective. Examples of such disease may include an infectious disease, an inflammatory disease, idiopathic thrombocytopenic purpura, agammaglobulinemia, the acute phase of Kawasaki disease, Guillain-Barré syndrome, and Churg-Strauss syndrome as vasculitis, preferably an infectious disease and an inflammatory disease, more preferably vasculitis. The indications of the artificial polyclonal immunoglobulin composition according to the present invention are not limited to those diseases, and the composition is applicable to any disease as long as the disease is a disease for which an immunoglobulin preparation is effective.

The present invention further provides a therapeutic method for an infectious disease or an inflammatory disease, the method including administering the artificial polyclonal immunoglobulin composition according to the present invention.

The present invention also provides the use of the polypeptides represented by the amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing, in the production of a pharmaceutical composition for the therapy of an infectious disease or an inflammatory disease.

The polypeptides as the active ingredients of the artificial polyclonal immunoglobulin composition according to the present invention may be produced by, for example, using a recombinant DNA technology. Specifically, the polypeptides may be produced by: first mixing plural kinds of genes encoding the plural kinds of the polypeptides; contacting the resultant gene mixture with appropriate vectors to make it incorporate therein; transfecting the resultant mixture of recombinant vectors into an appropriate host; culturing the resultant transformants to express the plural kinds of genes; and collecting a mixture of the polypeptides encoded by the genes from the culture, followed by purification.

A vector is not particularly limited as long as the vector is replicable on a host, and it is suitably selected depending on the kind of host and intended use. The vector may be obtained by extracting naturally existing vectors, or may be one in which one part of DNA segment other than a segment necessary for replication has been deleted. Representative examples thereof may include vectors derived from a plasmid, a bacteriophage, and a virus. The plasmid may be exemplified by a plasmid derived from Escherichia coli, a plasmid derived from Bacillus subtilis, and a plasmid derived from yeast. The bacteriophage may be exemplified by λ phage. The vector derived from a virus may be exemplified by vectors derived from animal viruses such as a retrovirus, a vaccinia virus, an adenovirus, a papovavirus, SV40, a fowlpox virus, and a pseudorabies virus, or vectors derived from insect viruses such as a baculovirus. Other examples of the vectors may include a vector derived from a transposon, a vector derived from an insertion element, and a vector derived from yeast chromosomal element. Alternatively, for example, there may be given a vector produced by combining those materials, such as a vector produced by combining genetic elements of a plasmid and a bacteriophage (such as a cosmid or a phagemid).

A vector is required to have a target gene that is incorporated in such a way as to allow the function of the gene to appear, and contains at least the target gene sequence and a promoter as components thereof. In addition to these components, as desired, one or more genetic sequences in combination selected from genetic sequences that encode information relating to replication and regulation, may be incorporated into the vector by using a well-known method. Such genetic sequences can be exemplified by a ribosome binding sequence, terminator, signal sequence, cis element such as an enhancer, splicing signal, and a selective marker. A selective marker can be exemplified by dihydrofolate reductase gene, ampicillin-resistant gene and neomycin-resistant gene.

As a method of incorporating the target gene sequence into the vector, any known method can be employed. For example, a method may be used which comprises treating the target gene sequence with suitable restriction enzymes to cleave it at specific sites, and then mixing it with a similarly treated vector DNA for ligation using a ligase. Alternatively, a desired recombinant vector can also be obtained by ligating a suitable linker to the target gene sequence, and then inserting it into the multi-cloning site of a vector suitable for the desired purpose.

Both prokaryotes and eukaryotes can be used as a host. Examples of the prokaryote include bacteria belonging to the Escherichia genus, such as, Escherichia coli, bacteria belonging to the Bacillus genus, such as, Bacillus subtilis, bacteria belonging to the Pseudomonas genus, such as, Pseudomonas putida, and bacteria belonging to the Rhizobium genus, such as, Rhizobium meliloti. Examples of the eukaryote include yeasts such as Saccharomyces cerevisiae and Schizosaccharomyces pombe, insect cells such as Sf9 and Sf21, and animal cells such as monkey kidney-derived cells, (COS cells, Vero cells), Chinese hamster ovary cells (CHO cells), mouse L cells, rat GH3 cells, human FL cells or 293 EBNA cells, and Xenopus laevis oocyte.

Introduction of a vector into a host cell can be performed according to a known method, for example, by applying a standard method described in publications (Sambrook et al., Eds., “Molecular Cloning, A Laboratory Manual, 2nd Edition”, 1989, Cold Spring Harbor Laboratory). When gene stability is a consideration, it is preferable to use a method that integrates the gene onto a chromosome. Meanwhile, it is convenient to use an autonomous replication system that utilizes an extranuclear gene. Specifically, calcium phosphate transfection, DEAE-dextran mediated transfection, microinjection, cationic lipid-mediated transfection, electroporation, transduction, scrape loading, ballistic introduction, infection, and the like, may be mentioned.

The polypeptides as the active ingredients of the artificial polyclonal immunoglobulin composition according to the present invention are each a fusion protein containing a heavy chain variable region (VH) and part of a heavy chain constant region (CH1) of an immunoglobulin. The heavy chain constant region of an antibody contributes to the stability of the antibody, and hence the polypeptides according to the present invention can provide an artificial polyclonal immunoglobulin composition having higher stability and a longer half-life in blood.

Thus, the polypeptides as the active ingredients of the artificial polyclonal immunoglobulin composition according to the present invention can be produced using Escherichia coli as host cells, and hence mass culture can be easily applied to the production. The polypeptides according to the present invention can be produced simply and in large amounts, and hence ensure stable supply thereof in large amounts.

The artificial polyclonal immunoglobulin composition according to the present invention contains multiple immunoglobulins as with a blood-derived immunoglobulin preparation. Thus, the artificial polyclonal immunoglobulin composition has an effect similar to that of a conventional immunoglobulin preparation. Further, as the artificial polyclonal immunoglobulin composition is artificially produced, the composition does not contain microorganisms such as a virus, resulting in an extremely low infection risk and very high safety.

Hereinafter, the present invention is more specifically described by way of examples. The present invention is by no means limited to the examples shown below. In the following examples, the collection of blood samples used for extracting immunoglobulin genes in all the cases was performed after the confirmation of the willingness of blood donors through informed consent.

Example 1

Cloning of human artificial gamma globulins, and mass culture and protein purification thereof were performed. As the human artificial gamma globulins, human single chain variable fragments (hScFvs) were produced, each of which were comprised of a heavy chain variable region, heavy chain constant region 1, and hinge region (VH-CH-hinge) of a human gamma globulin, by the method described in Japanese Patent Application Laid-open No. 2005-312445.

1. Cloning of hScFvs (FIG. 1)

Peripheral blood mononuclear cells (MNC) were isolated from peripheral blood of 20 healthy adults who gave informed consent, and total RNA was extracted therefrom and pooled by ordinary methods. Primers were made using consensus sequences at the 5′ end of VH and the 3′ end of a hinge region. Reverse transcription polymerase chain reaction (RT-PCT) was performed with the total RNA as a template and the consensus primers to afford polyclonal cDNAs encoding VH-CH1-hinge. The DNAs were added with a six histidine tag-encoding sequence at their 3′ end by using a 3′ end side primer having a sequence encoding six histidines added at the 3′ end, and were added with a sequence of 16 nucleotides homologous to the vector at their 5′ end. The cDNAs were incorporated into a pBAD vector by homologous recombination with an In-Fusion system to transform Escherichia coli by a heat shock method. 1,000 Clones of colonies of transformed bacteria capable of growing on an ampicillin-containing selective medium were picked up, from each of which plasmid DNA was extracted, and the nucleotide sequence of the cDNA being incorporated into the vector was determined through analysis by the Sanger method with a fluorescent terminator. Further, proteins were extracted from bacterial cells of each of the clones and were applied to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), which was followed by Western blotting with an anti-human Fab antibody to confirm whether or not VH-CH1-hinge was synthesized as a protein. Through sequence analysis, among 272 clones capable of expressing VH-CH1-hinge polypeptides, duplicate clones and clones whose VH-CH1-hinge structures had been broken (21 clones having undesired structures and 46 duplicate clones) were removed. Thus, 204 clones having unique sequences were finally obtained. Those clones were mixed to express recombinant proteins.

2. Mass Culture and Protein Purification of hScFvs

The clones expressing VH-CH1-hinge proteins obtained by the cloning were mixed in 500 ml of LB medium and cultured at 37° C. for 16 hours, and was added with glycerol at a final concentration of 15%. The resultant was dispensed into tubes at 10 ml each, cryopreserved at −80° C., and used as a master mix seed. The master mix seed that had been dissolved was added to 5 L of LB medium, and cultured at 37° C. for 6 hours. When OD600 reached 0.4 to 0.6, arabinose was added at 0.002% for the induction of expression. The resultant was further cultured at 37° C. for 16 hours, and bacterial cells were collected by centrifugation. The resultant bacterial cells were suspended in a Tris-ethylenediamine tetraacetic acid (Tris-EDTA) buffer (pH 8.0) and were added with Deoxycholic acid and lysozyme. The mixture was stirred at 37° C. to solubilize the bacterial cells. DNase I was further added to degrade the DNA of Escherichia coli, and the resultant was sufficiently solubilized by ultrasonication. The resultant suspension was subjected to high-speed centrifugation to collect a precipitated insoluble fraction (inclusion body). The insoluble fraction was washed with 3 M urea and collected by centrifugation. After that, the insoluble fraction was suspended in 8 M urea and left to stand at room temperature for one day and night to solubilize proteins of interest. The insoluble fraction was removed by high-speed centrifugation, and the supernatant was subjected to chromatography with a nickel chelate column (His-trap), to thereby isolate the proteins of interest. For further purification, the proteins were subjected to nickel chelate column (His-trap) chromatography again to be highly purified.

3. Removal (Reduction) of Endotoxin

The resultant purified proteins were found to include an endotoxin. In order to remove the endotoxin, the protein solution was dialyzed against a buffer obtained by rendering 6 M guanidine hydrochloride strongly alkaline, and was left to stand under the strongly alkaline condition for 3 days and nights to promote the hydrolysis of the endotoxin. Then, the degradation product was removed by 10K pore ultrafiltration. Thus, the endotoxin was reduced.

4. Results

There were obtained 204 clones encoding 204 different polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing. That is, 204 different hScFvs were obtained. The concentration of the endotoxin contained in the purified preparation obtained by purifying the mixture of the 204 different hScFvs was 10 to 5 ng/1 mg hScFv.

Example 2

The mixture comprised of plural kinds of hScFvs produced in Example 1 was investigated for the therapeutic effect on vasculitis by using SCG/Kj mice as spontaneous vasculitis model mice. The hScFv mixture used comprises 204 different polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing. The hScFv mixture was dissolved in 1.5% D-mannitol containing 0.45 M arginine (Arg), 0.45% glycine (Gly), and 0.9% sodium chloride before use.

First, the hScFvs were administered to 10-week-old SCG/Kj mice for five consecutive days at a dose of 10 to 40 mg/Kg/day through intraperitoneal administration (ip). At 13 weeks old, the mice were euthanized with CO₂ gas, and were each measured for its myeloperoxidase-specific anti-neutrophil cytoplasmic antibody (MPO-ANCA) level in serum as an indicator for vasculitis, spleen weight, and leukocyte count, lymphocyte count, monocyte count, granulocyte (neutrophil) count, and platelet count in peripheral blood. The therapeutic effect was evaluated based on the results of the measurements (FIG. 2).

It was observed that the administration of the hScFv mixture gave a reduction in the MPO-ANCA level in serum that is an indicator for vasculitis (FIG. 3). Further, a decreasing tendency of the spleen weight was observed (FIG. 4). In addition, the leukocyte count, lymphocyte count, monocyte count, granulocyte (neutrophil) count, and platelet count in peripheral blood decreased (FIGS. 5-A, 5-B, and 5-C). The above-mentioned results confirmed the therapeutic effect of the hScFv mixture.

The present invention is extremely useful in a medical field concerning diseases for which a therapy by immunoglobulin administration, e.g., IVIg, is effective, such as an infectious disease, an inflammatory disease, idiopathic thrombocytopenic purpura, agammaglobulinemia, the acute phase of Kawasaki disease, Guillain-Barré syndrome, and Churg-Strauss syndrome as vasculitis. 

What is claimed is:
 1. An artificial polyclonal immunoglobulin composition, comprising, as active ingredients, polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing.
 2. A pharmaceutical composition for treating an inflammatory disease, comprising polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing.
 3. A pharmaceutical composition for treating vasculitis, comprising polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing.
 4. A method of treating an infectious disease or an inflammatory disease, comprising administering an artificial polyclonal immunoglobulin composition comprising, as active ingredients, polypeptides represented by amino acid sequences set forth in SEQ ID NOS: 1 to 204 of the sequence listing.
 5. The method according to claim 4, wherein the infectious disease or the inflammatory disease is vasculitis. 